Up till now the modern microelectronics has been developing by way of successively reducing the microcircuit elements from micron to submicron size range. But ever increasing urgent demands in developing nanometric-size elements leads to search for novel techniques of lithographic formation of a conducting structure that assure high resolution which herein implies a minimum size of the elements of the conducting structure under development, that determines a limiting permissible density of a conducting structure elements per unit length or unit area without a contact therebetween.
One prior-art method of forming a pattern using electron beam (WO 95/26042). The method consists in placing an electron beam focusing system in the reaction chamber, arranging on the electron beam axis the mask and the wafer under processing coated with the layer of a material (photoresist) transformable when exposed to the effect of radiation. Then the wafer is irradiated with an electron beam, with the result that the material of the wafer surface layer undergoes transformation.
However, the aforementioned known method makes use of a widely spread technique of applying a layer of photoresist to the wafer, which technique allows of applying said layer having a thickness on the order of hundreds of nanometers (200 to 500 nm) which makes it impossible to obtain the pattern elements of a conducting structure having linear dimensions on the order of unities of nanometers.
Moreover, according to the known method, the conducting structure elements are formed successively so that whenever necessity arises to provide high density of elements per unit area of the structure being formed, e.g., a microchip, it requires a long period of time running into hundreds and even thousands of hours.
One more heretofore-known method of forming a metal-substrate conducting structure is known (U.S. Pat. No. 5,459,098) to comprise the steps of applying a metal nitride layer to a dielectric substrate and irradiating the latter with a concentrated (focused) laser beam, whereby the metal nitride is decomposed into a solid metallic conducting component which remains on the substrate, and a gaseous nonconducting component which is removed in the course of further carrying out the method. The metal nitride decomposition temperature lies within the range of from 100 to 1000.degree. C. The method is effected in a reaction chamber which is filled with an inert gas or wherein a required vacuum is established. A required pattern is formed from the conducting structure elements due to scanning the substrate surface with a laser beam according to a preset program, which affects adversely the production output of the method.
The method under consideration features but a low resolution because it is deemed impossible to obtain individual elements having linear dimensions on the order of unities and even tenths of nanometers. This is accounted for by the fact that to focus a laser spot to such a smallest size is a very difficult task. Besides, when a laser beam is incident on the layer of metal nitride the laser spot gets blurred due to heat conduction of metal, which results in increased linear dimensions of each individual element of the conducting structure. Therefore the method of photolithography is but of little use for forming conducting structure elements having linear dimensions in the nanometric range.
Moreover, as far as our knowledge goes, the known method in question fails to have found widespread industrial application because to provide long-length conducting structures, e.g., wire conductors in electronic circuits, a very prolonged period of time amounting to hundreds and thousands of hours is required.
Thus, every heretofore-known methods are featured by a multistage and labor-consuming production process; whenever a single-stage process is used it suffers from low production output which places limitation upon the range of practical application of said methods.